The pruritus of cholestasis is a difficult clinical problem to manage. Its etiology is unknown and current management is unsatisfactory. This form of pruritus can be so severe that it is an indication for liver transplantation. In the past few years, clinical and experimental data have suggested that increased neurotransmission via the endogenous opioid system contributes to the pathophysiology of cholestasis including the pruritus associated with it. We have shown that the behavior that results from pruritus, scratching activity, is associated with a circadian rhythm, which is also a characteristic of endogenous opioid receptors and ligands and of the perception of pain, a function mediated by endogenous opioids. Circadian rhythms are regulated via the pineal gland from external cues, including light, and it has been shown that pain perception can be abolished by turning off biochemical functions of the pineal gland with light. By analogy, manipulations of the pineal gland by light therapy may result in amelioration of pruritus. In this pilot study we will evaluate the effect of bright light phototherapy (BLPT) on the pruritus of cholestasis.